I live in the Arctic, and just went to the shed to get some DEF to put in my 2011 6.7. Warning light says I have 1200 km to go, so I figured I'd put a jug in. DEF jug frozen and expanded. No prob thawing out jug, but my question is about it freezing in the truck's DEF tank. If it's metal or plastic it'll split if full. Should I run it with just a gallon to not fill it up to prevent splitting? If the tank is heated, so what? It ain't heated when it sits in -30 overnight. (just got the truck in April, so this is the first real cold weather I've experienced with it. And first it called for DEF in a cold weather situation)

 

General consensus seems to be to avoid filling it full so that the neck allows room for expansion as it freezes. Also, you may want to put in at least 2.5 gallons to get back above the half tank sensor to reset miles to empty.

 

I wasn't aware that it could freeze. Is there an additive that I can add to avoid freezing entirely.

 

I wouldn't use it (any additive) or you run the risk of damaging the DEF system. It was designed to allow freezing. Don't fill it all the way and the heater will do it's job. I wouldn't worry about it.

 

You really should keep at least 3 gallons in there, maybe 4.

The def does freeze (obviously) but when you drive the truck the tank gets heated and the system works as designed.

As long as your truck is functioning properly, you need to keep def tank reasonably full and then don't give it another thought.

I'm surprised that the tank doesn't get heated along with the engine when you plug in the block heater, but it doesn't. If your def tank does get damaged, it's on Ford. Not you. (Unless you fill it overful and the def freezes and breaks the filler neck)

 

When you use the filler neck that came with def bottle you buy from ford it will only allow 5 gallons of def even when full there still room enough for def to expand when it freezes and pcm will not activate def pump if it's sees def temp is under 12 f it actuates the heater in sending unit keeps pool of def for the reductant injector

 

The trick is to fill it but not overfull so that it will have room to expand in the cold.


Use the ford fill spout to do this. It will stop adding when full. That will prevent any issues.

 

Follow the instructions in the manual. You can get the proper filling device from Ford to prevent overfilling. It seems the auto company took freezing into account. The tank and system is designed to handle freezing.

 

I wouldn't put any additives in. Freezing is not a problem but additives may be a problem.

 

Do not add anything to it, Then it would be contaminated...and no warranty to fix it.

 

Ditto to the above comments. Get a filler tube - FWIW - a lot of the 2.5 gal jugs have a filler tube with them, it works the same way as the Ford OEM one. I have both now. I would put at least a 2.5 gal jug in and see if the message resets. If it doesn't, add another gal and it should definitely reset. That is the countdown to idle only mode.

Also - not sure you have these since you said you live in the Arctic.. But pump DEF (bulk DEF) at truck stops will also not allow you to overfill either. There are none in Alaska - so it is quite possible you don't have any where you are at either.

 

So after reading replies to this post, checking out other threads and post on the subject, and asking guys up here about it, MY conclusion: #1 There is a heater in the DEF tank that thaws it when the truck is operating. (saw actual photos of the parts in another thread) #2 Do not fill it clear full in the winter. Not even full with the filler tube full. Run it above 1/2 full or a little more. When the warning/reminder message comes on, add a gallon or so. The tank will be about half full. This keeps you from counting down into a mode where the engine and speed is limisted until DEF is added. It won't split the tank if it freezes at 1/2 to 3/4 full. #3 I had trouble putting thawed DEF in the frozen tank. It took it ssslllooowww at first, then apparently as the DEF thawed out the frozen filler throat or whatever, it finally took it like it should. #4 Started the truck and the DEF warning/reminder message was still on. Instead of adding more, I followed my hunch and drove the truck for some errands. Yup, in about a half hour whatever thawed out and the warning/reminder message went out and found in my information screen it told me I had 1/2 tank of DEF. #5 As per Ford dealer. The only concern was to not fill it up with DEF in the winter. 3/4 at best.
#6 Don't live in the arctic!

Thanks for the input and help!

 

#6 has my vote!

 

Use the ford filler spout and then you won't overfill.


Run it down to about 200 miles then fill. It will operate better that way. There are plenty of warnings. You will not go into limp mode unless you run dry.

 

No. 7 Buy a gasser!